3 Ways to Extend C Drive in Windows 10 Easily

When your C drive is almost full and computer runs slower, you can extend C drive in Windows 10 or 11 via Disk Management, DiskPart, and a third-party free partition manager. Each one can help you increase C drive space easily.


By Emily / Updated on June 3, 2024

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Need to extend C drive in Windows 10

After using a computer with Windows installed for a long time, you may encounter a Low Disk Space warning on C drive. It is really a troublesome issue, especially for users whose work depends on computers such as game testers, editors, and designers. To fix it, apart from freeing up space on C drive via moving apps to another drive, running disk cleanup, and so on,  you can also try extending C drive.

How to extend C drive space in Windows 10

Usually, your C drive is the partition that contains OS information. Here we offer 3 effective and simple ways to increase C drive space in Windows 11, 10, 8, 7. You can choose one according to your demand.

Way 1. Extend C drive via Disk Management with adjacent unallocated space

If there is an adjacent unallocated space behind C drive, you can extend it in Windows 10/11 Disk Management. Here are detailed steps:

Step 1. Press Windows + R at the same time to open Run dialogue.

Step 2. Input diskmgmt.msc and hit Enter to open Disk Management.

Step 3. Right-click C drive and choose "Extend Volume".


Step 4. Follow the prompts that will appear to complete this operation.

Extend Wizard

Note: If the unallocated space is not adjacent to the C drive on its right side, the "Extend Volume" will grey out and cannot be clickable.

Extend Volume Grey Out

Way 2. Increase C drive via Diskaprt with contiguous unallocated space

When there is a contiguous adjacent unallocated space behind system partition, you can also choose to extend it in Diskpart utility.

Step 1. Open Run dialogue, input diskpart and click OK.

Step 2. Run commands as follows:

list disk
select disk n: n refers to the number of the disk that holds C drive.
list partition
select partition m: m is the number of C drive.
extend size= x: x is the size in MB you want to add to the system partition.

extend partition

Note: Same as the Disk Management, the DiskPart can only extend C drive when there is an adjacent unallocated space on its right side.

Way 3. Increase C drive space in Windows 10 with non-adjacent unallocated space

From the previous content, we know that Disk Management and DiskPart have the same restriction: only extend a volume when a contiguous unallocated space follows it. Besides, they can extend NTFS partition only. If the C drive is of FAT32 file system, they cannot help you, either.

In such cases, you had better employ third-party partition manager software, such as AOMEI Partition Assistant. This software can extend C drive more flexibly. For example, it can directly merge unallocated space, no matter where it locates on the hard disk, into the C drive by 3 steps. Besides, you can move partition to make unallocated space adjacent to the to-be-extended partition and then extend it successfully. You can free download the demo version to see how to extend C drive in Windows 10.

AOMEI Partition Assistant

The Best Windows Disk Partition Manager and PC Optimizer

Make sure there is free unallocated space on the disk.
Make sure all the running applications in the partition that you are going to operate have been closed.
Don't cut off power until the task has finished.

Step 1. Install and run AOMEI Partition Assistant. Right-click the C drive and select "Advanced" > "Merge Partitions".


Step 2. Tick the unallocated space and click on "OK".


Step 3. Finally, click "Apply" to commit the pending operation.


See? Only 3 simple steps can make it done! Besides, you can upgrade to Professional edition which offers two other methods to extend C drive in Windows 11/10/8/7. One is "Allocate Free Space", which can directly allocate some free space from one drive to another; while the other is “Extend Partition Wizard”, both can solve your problem of how to increase C drive space in Windows 10. The following shows how to use the "Extend Partition Wizard".

Step 1. Run AOMEI Partition Assistant Professional. Click Tools > Extend Partition Wizard on the main interface.

All Tools

Step 2. In the pop-up window, there are two choices. To expand system click Extend system partition and then click Next.

Extend Partition Method

Step 3. Click the partition which you want to add free space from then click Next to continue.

Select Partitions

Step 4. Right move the bar to decide the size of free space you need to add into C drive. Then click Next.

Extend Size

Step 5. Click Proceed to operate the task then you can extend C drive.


AOMEI Partition Assistant Professional is available for Windows 11, Windows 10, Windows 8.1/8, Windows 7, Windows Vista and Windows XP; if you are Server users, AOMEI Partition Assistant Server is suitable for you.

Further reading: Upgrade C drive space once and for all

In fact, if you have a disk without large storage space, then basically, your C drive can't possess much available space. So, if your disk space is not enough for your daily work, then, we suggest you upgrade your disk to a larger disk. You don't need to worry about data loss. AOMEI Partition Assistant has disk clone function to help you safely clone the whole disk without data loss. After you initialize a new disk, you can click "Disk Clone" feature to upgrade your disk.

Clone disk

Final words

Obviously, it’s not hard to extend C drive in Windows 10/11 even though there is no contiguous unallocated space behind it. Among the three listed solutions, choose one based on the specific situation. Apart from increasing system drive in Windows 10/11, the AOMEI Partition Assistant software also has many other functions: migrate OS to SSD, split a large partition into two smaller partitions, clone hard drive (SSD, HDD, SD card, USB flash drive), align SSD partitions and more.

FAQs about extending C drive

What are the limitations of using Disk Management to extend the C drive?
Disk Management can only extend the C drive if there is unallocated space immediately adjacent to it on the same disk. If unallocated space is not adjacent or if there is an extended partition in between, you may not be able to extend the C drive using Disk Management.

Are there any risks involved in extending the C drive?
Extending the C drive involves making changes to your disk partitions, which carries a risk of data loss if not done correctly. Always back up important data before attempting any disk management operations.

Can I extend the C drive without reinstalling Windows?
Yes, you can extend the C drive without reinstalling Windows, as long as you have available unallocated space and follow the appropriate procedures. Extending the C drive should not affect your Windows installation or data if done correctly.

Emily · Staff Editor
Emily is an English editor of AOMEI Technology; she has a great passion for providing easy solutions for people to tackle with all disk or partition management problems. In addition to writing articles about disk/partition management, she also edits great tutorials on how to back up and restore disk for data security. In her spare time, she loves to learn computer skill to improve herself or stay with her family to enjoy a good day.